Moesly Seacraft 21 repower opinions

[Bushwacker]

I think outboards would be a LOT more expensive than staying with an I/O. If they were mounted on transom, balance would probably be ok although shifted aft a bit relative to the I/O, but cutting the transom to mount outboards and building a splashwell would also be BIG job and not retain the configuration Gillie likes.

Would not recommend a bracketed outboard like Brian used, as it would significantly change balance of the boat. In addition to adding the bracket, he also removed the windshield and big fiberglass seats up front to install a CC, further increasing the aft CG shift. One of the video's he posted of the boat running in a light chop showed some porpoising which the stock boat NEVER did. The bow on the stock configuration Unohu and Island Trader's 21 hardly bounced at all in 2-3' seas, so I've concluded that those mods adversely affected the balance and ride of the boat. I think Gillie is on the right track in staying with the I/O. Only question is whether a modified I-6 or stock V-8 is the most cost effective route.

[jtharmo]

I agree with all you said. Just a thought exercise based in nostalgia and vanity.

[SandlapperGT]

Thanks Bush,

I agree the outboard conversion would be more work and likely more expense. I was just wondering from a performance standpoint. The SC 21Ms are so rare.

I have read ITs thread but dont remember seeing any performance numbers on his (or Brian's for that matter).

I don't think (and I may be way wrong) that the SC 21M was every considered a speed demon, but that it could maintain higher speed in rough ocean conditions.

[McGillicuddy]

Sandlapper,
I had a Seavette with twin 2.4 l merc 200 with 225 carbs on transom. Previous owner got 68mph on radar gun. I would guess 60-65 would be a possibility with a pair of light ones.


SSPBill,
I concur a pair of 300 lbs 115s towers would be cool. But I'm looking for range and economy.
Skip and Carla are putting twin Etec 115s on outer strakes on their 21. That will provede added stability and allow them to frolic in the shallows around the keys. The hull will plane with a single 115.

[bgreene]

Go Outboard.........a lot less maintenance

Evinrude etec G1 200 HO, or if rated for more, go with the 250HO.
Evinrude got the etec correct right out of the box......1st year 2005.
I have one from that year and it's been perfect since.
Highly refined outboard...........starts immediately warm or cold and go..........very quiet too.

[SandlapperGT]

Hi McGillicudy,

That is really impressive! A hull that planes that slow on so little power, with the ability to maintain speed in rough conditions but can still hit 60-65 conditions permitting. It sucks there are so few around....

I think I read that the Formula 233 gets very squirrelly above 50 unless a lot of work is done to remove the hook. Even then I don't think it is as efficient, or can handle the conditions your 21 can.

While I can't wait to start renovation on my project 23, I am scared my heart will never be true to her and will always be looking for a 21...

ETA: Sorry for the derail....

[McGillicuddy]

Bgreene,
Yeah outboards are sweet. I do like the etec 2.6 L for this ride but I don't think I have the funds or motivation to cut the transom and hang one. If the boat were more beat up, I'd probably give it a more serious look. Not off the table as I just came across some 2011 200's with around 400 hrs for $6500.

Sandlapper,
Appreciation of other boats is a passtime. Your 23 is a great boat, and in fact my first interest in Seacraft was spawned by a 23 Sceptre. I couldn't afford that one at the time, but I bought the first 20 Seafari I saw shortly thereafter. Eventually bought a Seavette, just to save it from the dump. Only sold it because I didn't have the heart to alter it, and the 21 was on its way.

Good luck with your 23 project!

[Bushwacker]

Originally Posted by SandlapperGT

. . . I don't think (and I may be way wrong) that the SC 21M was every considered a speed demon, but that it could maintain higher speed in rough ocean conditions.

Merc did a bunch of tests at Lake X back in the 60's and found that the VDH hull was about 10% faster than a conventional constant deadrise deep V of the same weight and horsepower, so the early SeaCrafts had a reputation for being pretty fast boats. What is really amazing is that all of the Moesly designs, if powered with the engines they were designed for, seem to be able to plane at about 12 mph! Don't think a similar vintage Formula, Bertram or Donzi will even come close to that!

I spent a lot of time under the 20' hull when I painted the bottom on my boat, and discovered some subtle details that show how brilliant Moesly was as a hull designer, despite no formal training as a naval architect:
1. The outer panel has a slight wedge built into it in the aft 10', which you can see if you sight along the chine back toward the transom. This helps the boat get on plane at low speed.
2. Since the hull develops more lift as speed increases, the hull rides higher in the water at high speed, so the outer panels are almost completely out of the water at about 40 mph. This means that the wedge built into the outer panels does NOT limit max speed as it would on a constant deadrise design.
3. Since the inner panel is carrying most of the load at high speed, Moesly incorporated a little bit of rocker into the inner panels, which allows the bow to rise at high speed to reduce wetted surface for less drag and more speed! If you look at the Boating Magazine test of the 20' Seafari in the Literature section, you'll see that sure enough, the running angle increases from a very flat 0.5 degrees at 32-36 mph to 1.25 degrees at almost 40 mph! I've noticed this in my own boat and think it's an absolutely brilliant design detail that very few people are aware of!

As for "not being a speed demon", what you have to remember is that the outboards available in the early 60's were fairly small. Moesly raced the early 21's with a pair of 110 hp Mercs which is why he didn't run much over the mid 40's. It's actually a pretty fast hull if you add more power, and I think Island Trader has seen well over 50 mph with that 383 stroker motor he put in his 21! But you're right, the boats rode so well in rough conditions that Moesly was very competitive with and often beat 30' inboards running twin 500 hp I/O's! And most of us that run offshore are more impressed with rough water speed capability than ultimate speed in flat water!

[Islandtrader]

Gillie;
Remember you can only be original once! If you don't do any other mods, and you throw the OB on her she now becomes a modified mutt. I would go in line or SBC. The only thing on a sb, would you have to split your engine box for it to fit?

[McGillicuddy]

Originally Posted by Islandtrader

Gillie;
Remember you can only be original once! If you don't do any other mods, and you throw the OB on her she now becomes a modified mutt. I would go in line or SBC. The only thing on a sb, would you have to split your engine box for it to fit?

Thanks Terry.
I concur. I am very much leaning toward the inline. Haven't figured out the fine details of the stroked inline yet but I'm really leaning that way.

I was very impressed by your expansion project but I'm not that gifted. Granted, a sbc would be a more logical choice, I love the inline idea. Any feed back on drive choice and compatibility would be appreciated.